Test the proxy

The current t/80proxy.t is isolated from the rest of the test suite so actually
tests very little, and what it does test is duplicating other tests.

Ideally the proxy should be tested in the same way as DBI::PurePerl. In other
words, by creating wrappers test files for each test file that set
$ENV{DBI_AUTOPROXY} and run the original test. They'll also need to start and
stop a proxy server.

Fixing bugs

Naturally I'll offer direction and guidance on any you want to tackle.
I've also got a few that could be entered into rt.cpan.org.

Others

General:

Protect trace_msg from SIGPIPE?
prepare(...,{ Err=>\my $isolated_err, ...})
Add trace module that just records the last N trace messages into an array
and prepends them to any error message to provide context for the error.
Document DBI_PROFILE_FLOCK and LockFile attrib in DBI::ProfileData and DBI::ProfileDumper